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Circulatory System
Transport in small invertebrates
Sponges
Cnidarians
Flatworms
Transport in invertebrates
Roundworms
Fluid contained within the body cavity (pseudocoelome) functions to transport nutrients and
wastes but these animals do not have a heart or blood vessels.
Diffusion is insufficient for
transporting substances over long distances
It takes 1 second for glucose to diffuse 100 micro meters
It will take 3 hours to diffuse 1 cm!
Circulatory systems solves this problem by bring molecules close enough to each cell
In an animals body
Open Circulatory System
blood is pumped from the heart through blood vessels but then
it leaves the blood vessels and enters body cavities,
where the organs are bathed in blood.
Mollusks and arthropods: (except cephalopods)
have an open circulatory system.
Open Circulatory System
Arthropods
Crustaceans and some arachnids have hemocyanin (instead of hemoglobin)
a oxygen carrying protein with copper (instead of iron)
The blood of insects is colorless
because it lacks respiratory pigments;
Blood functions to carry nutrients, not gases.
Consequences:
Animals with open circulatory systems
generally have limited activity due to
limitations in the oxygen delivery capability
Insects are able to be active
because gas exchange is via a tracheal system.
Closed Circulatory System
Blood is contained within blood vessels.
Valves prevent the backflow of blood within the blood vessels.
This type of circulatory system is found in vertebrates and
several invertebrates including annelids, squids and octupus
Closed Circulatory System
Earthworms
have a dorsal and ventral blood vessel that runs the length of the animal.
Branches from these vessels are found in each segment.
There are five vessels (hearts)
that pump blood from the dorsal vessel to the ventral vessel.
Earthworms have red blood (due to the pigment hemoglobin) but they have no cells.
Hemoglobin binds with oxygen to carry it to the tissues.
Parts of the circulatory system and their functions
PUMP:
Atria: __________________
Ventricles: ______________
PLUMBING:
Arteries: __________________
Veins: ______________
Capillaries: _____________
Function of pulmonary and systemic circuit?
Form reflects function
Atrium: (thin walled)
Arteries have _______layer of muscle
Ventricle: (thick walled)
Veins have _______layer of muscle
Why is the left ventricle thicker?
Capillaries have _______layer of cells
How is backflow prevented?
Capillaries are the sites for diffusion
Closed circulatory system in fish
Single circuit: blood travels to gills and body before returning to the heart, disadvantage?
__________________
Consequence: The activity level of fish is limited!
Closed circulatory system in amphibian
Amphibians have double circuit
The advantage is_____________________________
but one ventricle that receives
Both oxygenated and deoxygenated blood
The disadvantage is________________________
Closed circulatory systems in mammals and birds
Birds and mammals (also crocodilians)
have a four-chambered heart
which acts as two separate pumps.
the high rate of oxygen-rich blood flow
through the body enables birds and mammals
to maintain high cellular respiration rates
(which allowed for endothermy)
One million persons die each year of a heart attack
Damage to walls of arteries due to
smoking and inactivity
PLUS
diet high in trans fats/ sat fats and low in unsat fats
Causes: Atherosclerosis
(buildup of plaque in arteries, reducing flow)
Which can happen in coronary arteries
( supply blood to the heart muscle)
Leading to a heart attack
(failure of the heart to function properly)